Purpose: To assess the usefulness of multi-detector row helical CT (MDCT) in detection and sizing of acute and chronic myocardial infarction (MI).
Methods and Materials: Seventeen patients underwent MDCT and MRI in the acute stage (within 2 weeks, n = 5) and chronic stage (6-12 months, n = 12) of MI. First-pass and 5-minutes and 15-minutes delayed myocardial MR imaging was performed using an 1.5 T scanner (GE Signa CVi) with injection of Gd-DTPA (20 ml in total amount, 3 ml/sec speed) to assess the extent of MI. Within 24 hours after MR imaging, ECG-gated MDCT was performed using GE 4-slice or 16-slice scanner at 25-seconds and 15-minutes delay. Total contrast amount was 120 ml (Iomeron 300) and speed was 4 ml/sec. Short-axial CT images of 2 mm slice thickness were reconstructed from the CT data. Two radiologists analyzed the perfusion defects and hyperenhanced area on MR and CT images and calculated the percentage of lesion to total left ventricle wall area. The calculated values of the two observers were averaged and statistical analysis was performed for comparison of two modalities.
Results: In all cases, MDCT showed lesions of MI on early and late phase images. The percent area of the lesion on MDCT images (early and late phases) correlated well with that of MR images (perfusion and delayed images). The correlation coefficient was 0.75 between perfusion MR and early CT, 0.84 between 5-minutes delay MR and late CT and 0.89 between 15-minutes delay MR and late CT, respectively. There was significant difference in % lesion size between perfusion MR (7.4 ±3.7%) and early CT (9.2 ±4.5%) (p = 0.03), between 5-minutes delay MR (15.0 ± 8.8%) and late CT (12.1 ±7.6%) (p = 0.02), and between 15-minutes delay MR (14.2 ±8.7%) and late CT (p = 0.04), respectively.
Conclusion: Myocardial perfusion imaging is feasible with multi-detector row helical CT. The size of MI on early phase MDCT is significantly larger than that of MR imaging.
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